Blacks are known to have an incidence of hip fractures that is one third that of whites. Studies are going to determine the mechanism for greater bone mass that occurs in blacks. Results to date indicate that blacks have a low rate of bone turnover as compared to whites and alteration of the vitamin D-endocrine system, increases in serum immunoreactive PTH, serum 1,25(OH)2D and urinary cyclic AMP and decreases in serum 25-OHD and urinary calcium.